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October 14, 2008

Vision Loss More Prevalent In Diabetics

by Sam Savage

Visual impairment appears to be more common in people with diabetes than in those without the disease, according to a report in the October issue of Archives of Ophthalmology, one of the JAMA/Archives journals.

Approximately 14.6 million Americans had diagnosed diabetes mellitus in 2005 and another 6.2 million had undiagnosed diabetes, according to background information in the article. It is estimated that the number of individuals with diagnosed diabetes will increase to 48.3 million by 2050. "Diabetic retinopathy [damage to the retina caused by diabetes], one of the most common microvascular complications of diabetes, is considered to be one of the major causes of blindness and low vision," the authors write. Although studies suggest that controlling glucose and blood pressure have reduced the rate of retinal diseases, other ocular conditions suffered by diabetic patients, such as cataract and glaucoma, may increase the risk of visual impairment. Additionally, decreased vision caused by an abnormal shape of the cornea is also common among people with diabetes.

Xinzhi Zhang, M.D., Ph.D., and colleagues at the Centers for Disease Control and Prevention, Atlanta, used data from the National Health and Nutrition Examination Surveys from 1999 to 2004, which included 1,237 adults with diabetes (average age 59) and 11,767 adults without the disease (average age 45) and also measured their visual acuity before and after optical correction. Participants' vision was tested while they were wearing any glasses or contacts they typically used, and their demographic information was also noted.

An estimated 11 percent of American adults with diabetes had some form of visual impairment (3.8 percent uncorrectable and 7.2 percent correctable), while only 5.9 percent of those without diabetes had some form of visual impairment (1.4 percent uncorrectable and 4.5 percent correctable). "People with diabetes were more likely to have uncorrectable vision impairment than those without diabetes, even after controlling for selected other factors," the authors write. "Our findings also suggest a strong association between visual impairment (correctable and uncorrectable) and older age, member of racial/ethnic minorities, lower income and lack of health insurance, all independent of diabetes status."

"The high prevalence of visual impairment among people with diabetes indicates a need for diverse public health strategies to reduce the burden of both correctable and uncorrectable visual impairment," the authors conclude. "It is important to identify and pursue ways to increase access to eye care for everyone and to correct visual impairment, where possible, to diminish morbidity and mortality due to impaired vision."